trixie - Anatomy and physiology (brain tumor).doc

8/9/2019 trixie - Anatomy and physiology (brain tumor).doc

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Anatomy and physiology

The brain is one of the largest and most complex organs in the human body. It ismade up of more than 100 billion nerves that communicate in trillions of connectionscalled synapses. The brain is a spongy organ made up of nerve and supportive tissues.

It is located in the head and is protected by a bony covering called the skull. The base,or lower part, of the brain is connected to the spinal cord. Together, the brain and spinalcord are known as the central nervous system (!"#. The spinal cord contains nervesthat send information to and from the brain. The !" works with the peripheral nervoussystem ($!"#. The $!" is made up of nerves that branch out from the spinal cord torelay messages from the brain to different parts of the body.

Structure and function of the brain

The brain is the body%s control center. It constantly receives and interprets nervesignals from the body and responds based on this information. &ifferent parts of the

brain control movement, speech, emotions, consciousness and internal body functions,such as heart rate, breathing and body temperature. The brain has ' main parts cerebrum, cerebellum and brain stem.


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Cerebrum

The cerebrum is the largest part of the brain. It is divided into ) parts (halves# called theleft and right cerebral hemispheres. The ) hemispheres are connected by a bridge ofnerve fibres called the corpus callosum.

The right half of the cerebrum (right hemisphere# controls the left side of the body. Theleft half of the cerebrum (left hemisphere# controls the right side of the body. The outer surface of the cerebrum is called the cerebral cortex or grey matter. It is thearea of the brain where nerve cells make connections, called synapses, that controlbrain activity. The inner area of the cerebrum contains the insulated (myelinated# bodiesof the nerve cells (axons# that relay information between the brain and spinal cord. Thisinner area is called the white matter because the insulation around the axons gives it awhitish appearance. Cerebellum

The cerebellum is the next largest part of the brain. It is located under the cerebrum atthe back of the brain. It is divided into ) parts or hemispheres and has grey and whitematter, much like the cerebrum. The cerebellum is responsible for:

movement

posture

balance

reflexes

complex actions (walking, talking#

collecting sensory information from the body

Brain stemThe brain stem is a bundle of nerve tissue at the base of the brain. It connects thecerebrum to the spinal cord and sends messages between different parts of the bodyand the brain. The brain stem has 3 areas:

midbrain

pons

medulla oblongata


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The brain stem controls:

breathing

body temperature

blood pressure

heart rate

hunger and thirst

The cerebrum is further divided into * sections called lobes. These include the frontal(front#, parietal (top#, temporal (side# and occipital (back# lobes.

+ The frontal lobes are responsible for problem solving and udgment and motorfunction.+ The parietal lobes manage sensation, handwriting, and body position.+ The temporal lobes are involved with memory and hearing.+ The occipital lobes contain the brain-s visual processing system.


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Cranial nerves and their functions

Number Name Function

I olfactory smell

II optic vision and light detection by the pupil

III oculomotor eye movement upward, downward or inwardnarrowing and widening of the pupillifting of the eyelid

I trochlear eye movement downward and inward

trigeminal facial sensationchewing

I abducens outward eye movement

II facial facial expressionclosing of the eyelidtaste in the front part of the tongue

III acoustic hearingbalance

I! glossopharyngeal swallowinggag reflexspeech

! vagus swallowinggag reflexspeech (vocal cords#control of muscles in internal organs

!I accessory neck turningshoulder shrugging

!II hypoglossal tongue movement

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trixie - Anatomy and physiology (brain tumor).doc